Flasher lamp



Nov. 25, 1958 G. B. DAVIS, JR

FLASHER LAMP Filed June 50, 1955 OFF OFF

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nvJI-r-Iav-JIIIIIIIIII FLASHER LAMP George B. Davis, J12, Glen Mar Park,Md.

Application June 30, 1955, Serial No. 519,199

3 Claims. (Cl. 31547) This invention relates generally to flasher lampsand more particularly to an improvement in a lamp of this type whereinby the arrangement of a relatively large heat absorbing mass about thethermal responsive circuit controlling element ofthe lamp, the flashingrate of the lamp is materially reduced in addition to providing a lampunusually dependable and positive in operation.

With lamps of the flasher type wherein the circuit controlling elementof the lamp is activated by heat from the lighted filament, regulationof the flashing interval has, heretofore, been most difficult tocontrol. One reason therefor being that all adjustment of the thermalelement must be completed prior to assembly of the mechanism within thesealed glass envelope of the lamp. Primarily, however, the unusuallyfrequent failure of such lamps can be attributed directly to the heatingrate of the thermal control when exposed to direct radiation from thefilament. When heating and cooling of the element occurs too rapidly,the element lacks the necessary over-travel to maintain it at either ofits circuit controlling positions the time required to produce thepositive flashing elfect desired.

Additionally, for the aforementioned reason, prior lamps of this typeare frequently highly position sensitive often to the extentof beingspasmatic in operation in one position while completely inoperative inanother. When the arrangement of the lamp in use is such as to place thefilament above the element, the heat biasing force on the element oftenis insuflicient to positively drive the element to either of its circuitcontrolling stations but leaves the element oscillating just at itsmaking and breaking point instantaneously responding to the heating andcooling of the filament to result in a flickering of the lamp mostannoying to the observer.

While the arrangement of the present invention retains all theadvantages of prior such devices, the aforementioned disadvantages arealleviated by inclosing the thermal control of the lamp with asufliciently large heat absorbing mass applicable during operation ofthe filament to shield the element until the mass, relatively close tothe filament, has absorbed the necessary heat to maintain the element inoperated position long after heat is no longer forthcoming from thefilament. By this arrangement, operation of the thermal control becomesrelatively independent of the operating interval of the filament toresult in a lamp considerably more positive in function in addition topossessing the highly desirable characteristic of being abnormally slowin operation, a feature long sought after in a lamp of this type.

It is an object of the present invention to provide a new and improvedlamp of the flasher type unusually slow and positive in operation.

A further object is to provide an improved flasher lamp wherein by thearrangement of a relatively large heat absorbing mass about the circuitcontrolling thermal responsive element of the lamp the rate of heatingand cooling of the element is materially reduced.

An additional object is to provide an improved flasher atent O 'i ceM2345 Patented Nov. as, was

lamp wherein the flashing rate is regulated by controlling the rate ofheating and cooling of the thermal responsive circuit controllingelement of the lamp.

A still further object is to provide a new and improved flasher lampinexpensive to manufacture, rugged in construction in addition to beingcompletely reliable and positive in operation.

This invention will be better understood by reading the followingdetailed description with reference to the accompanying drawingswherein:

Fig. 1 is a view in elevation of the mechanism of the invention asmounted within the glass envelope of the lamp shown partly cut away;

Fig. 2 is a fragmentary sectional view, partly cut away, of the heatabsorbing mass and thermal element of Fig. 1 as arranged between thefilament leads of the lamp;

Fig. 3 is a plan view of a graph comparatively illustrating the cyclingrate of the present invention with respect to the flashing rate ofconventional flasher lamps of this type;

Fig. 4 is a side view in elevation of an alternate form of the inventionas viewed through the partly cut away section of the glass envelope ofthe lamp;

Fig. 5 is an enlarged fragmentary view partly in section of theinvention as shown in Fig. 4 looking down upon the assembly.

Fig. 6 is an enlarged fragmentary view partly in section of theinvention of Fig. 4 and rotated clockwise 45;

Fig. 7 is a view in section of an alternate form of the invention assupported between the leads of the lamp, and

Fig. 8 is a side view in elevation showing an arrangement of theinvention as used in combination with a multiple filament lamp.

Referring now to the drawings and more particularly to Fig. 1 thereof,the lamp of the present invention is shown as including an insertingscrew shell 5 suitably formed for being received within the usualincandescent lamp receiving sockets not shown. Upon the shell 5 isconventionally mounted a glass envelope 6 wherein is substantiallycentrally supported by leads 7 and 8 a length of coiled filament 9. Fromthe filament, the leads 7 and 8 extend downwardly through the envelopeto connect in the usual manner with the shell and base terminals 3 and 4of the inserting shell 5 whereby operating current is supplied to thefilament of the lamp.

Spot welded, as at 10, to the lead 7 is a strip of himetallic element 11preferably of the high temperature low deflection type. The free end ofthis strip is initially spaced from the lead 8 but so arranged withrespect thereto as to deflect into electrical contact with this lead atsuch time as the strip becomes sufficiently heated. -Incircling thestrip 11 over substantially its entire length is an annular insulatingmass 12 preferably formed from ceramic, however, variously constructedmasses of other materials have proven completely satisfactory for thepurpose. Commonly secured with the strip 11 to the lead 7 is a metallicbar 13 so for-med at 14 as to engage and forcibly maintain the mass 12snugly against the lead 7 leaving the unattached end of the strip freeto flex into contact the lead Sduring operation of the lamp, as will now.be described.

As current is applied to the terminal surfaces 3 and 4 of the insertingscrew shell 5 to pass by way of leads 7 and 8 to the filament 9, thelatter is heated to a state of incandescence referred to generally asthe on interval of the lamp. Instead of heat from the filament beingapplied directly to the thermal strip 11, as commonly is the case withflasher lamps of this type, heat from the filament is first communicatedto the mass 12 which functions to absorb this heat at a rate dependingupon the characteristics of the material from which the mass is formed.As the temperature of the mass rises a portion of this absorbed heat iscommunicated therethrough to the strip 11 causing its gradual rise intemperature and deflection toward the lead 8. When the mass becomessufficiently heat saturated as to effect movement of the strip intocontact with the lead 8 a greater portion of the current, previouslypassing through the filament 9, is now shunted therefrom through thestrip 11 with the resultant cooling of the filament and consequentialinterruption of the heat source to the mass. However, before thisshunting operation occurs, the mass 12 will have taken on considerableheat which thereafter continues to pass to the thermal strip 11maintaining the latter in operated position against the'lead 8 longafter the strip would normally have cooled and moved from its shuntingposition. When the mass has sufficiently cooled to allow separation ofthe strip from the lead 8 permitting current to again resume its coursethrough the filament, the mass 12, acting as before, serves to shieldthe strip from the filament heat that normally would immediately drivethe strip back into contact with the lead 8 thusly to effect a slowequally spaced flashing of the lamp heretofore unobtainable with lampsof this type.

Fig. 3 is a graph illustrating comparatively the difference in cyclingrates between conventional flasher lamps and the device of the presentinvention. The vertical lines 15 indicating time in seconds with 16representing the cycling rate of the present lamp as compared with 17representative of the operating cycle of previous flasher lamps of theincandescent type.

The advantages of this slow operating feature of the present device ismore apparent when employed in combination with strings of ornamentallights such as the type frequently used for Christmas tree lightingwherein the slow positive flashing produces an effect in the order of ashimmering or twinkling of the lights rather than the expectant rapidflashing customarily associated with conventional flasher apparatus ofthis kind. When a sufficient delay, as provided by the present'device,follows the operation of a lamp, it is onlywith difficulty and carefulobservation that an observer can distinguish which lamp is actuallyflashing. Generally, when several of such lamps are so used, one is onlyaware of a restful shifting of the light from one position on the treeto another. Additionally, when such a lamp as shown in Fig. 1 isconnected in a series of ornamental lights of the type specified,current from the flashed lamp is shunted to the remaining lamps of theseries to slightly increase their brightness. As the strip 11 cools andseparates from the lead 8 allowing current to again resume its coursethrough he filament, the remaining lamps deminish in brightness to theirnormal state. The effect produced, particularly when sufliciently slowand positive, is distinctly different and pleasing from that obtainablewith conventional flasher arrangements that operate to simultaneouslyflash all the lamps of a series wherein such apparatus is connected. 7

Fig. 4 is an alternate form of the invention preferably for use in amultiple connected circuit as compared to the device of Fig. 1 which isspecifically designed for use in combination with series connected[assemblies such as hereinbefore described. Fig. 4 shows the insertingscrew shell 19 as supporting the glass envelope 20. Leads 21 and 22,extending upwardly from the terminals of the shell, pass through theenvelope to connect with the circuit controlling mechanism of the lampas shown to advantage in Figs. 5 and 6.

Spot welded at 23 to the lead 21 is a strip of bimetallic element 24.'By reason ofthe confined space within which this element must operate,this strip, like strip 11 of Fig. 1, should be of a high temperature lowdeflection type. The initial positioning of the strip is such as to bearagainst a dummy lead 25 mounted with leads 21 and 22 within the pinch26. A laterally extending bar 27, secured as by welding to the dummylead 25, is arranged for connecting with one end of the filament 35 at28 with the other end of the filament similarly connected at 29 to thelead 22. The filament 35 is shown as closely supported about the heatabsorbing mass 36 of the lamp by radially extending members 37, however,it will be readily understood that divers other methods of arranging andsupporting the filament about the mass 36 may be resorted to withequally satisfactory results.

The mass 36 is so formed with grooves 31, Fig. 5, as to closely fitbetween leads 21 and 22 whereupon as the short end portions 32 of theleads are thereafter formed over the mass, as shown to advantage in Fig.4, the mass is properly maintained in spaced relation with respect tothe strip 24 leaving the latter free to flex into and out of electricalcontact with the lead during operation of the lamp, as will now bedescribed.

Current admitted to the lamp by way of terminal of the inserting screwshell 19, passes through the lead 21 to the bimetallic strip 24 and onto the dummy lead 25 against which the strip normally rests. From thelead 25 the circuit continues through the bar 27, the filament 35 andback to the lead 22 and to the other terminal 31 of the shell. Ascurrent is applied in this manner to the filament to effect the heatingthereof, a portion of the heat from the filament passes to the mass 36and from thence to the strip 24 to effect the heating thereof. As thetemperature of the strip gradually rises to overcome its initial biastoward the lead 25 and separates from the lead, circuit through thefilament thereupon is interrupted to effect an extinguishing of the lampand consequently a cooling of the filament. However, with cooling of thefilament, the stored heat in the mass continues to pass to the stripmaintaining the latter in open circuit position with respect to the lead25, long after the strip would normally have cooled and returned tocontacting position with the lead 25 again to effect the lighting of thelamp. By such an arrangement the flashing rate of the lamp is materiallyreduced while the operating'characteristics are preportionally improved.

Fig. 7 is an alternate form of the invention wherein the mass 40 is inthe form of a length of metallic tubing of any size or shape suitablefor the purpose. The bimetallic element or strip 41, after being securedas by pinching within one end of the tube as herein shown, is thenfastened with the tube to the lead 42 in such a manner that the free endof the strip is positioned for deflecting into electrical engagementwith the lead 43. When such occurs, current is shunted from the filamentin a manner to effect a flashing of the lamp. By the arrangement here inshown, the strip is completely shielded from radiated heat from thefilament in addition to possessing certain other advantages obtained byclosing one end of the tube which serves to some extent to increase theefliciency of the mass 40. The functioning of a lamp when so constructedclosely corresponds to that of Fig. 1 even though the mass of the tube40 is considerably less than the masses 12 and 36.

Fig. 8 shows an alternate form of the invention suit- .able for usewithin either a multiple or series connected filament sections areenergized, heat is applied to the mass 54 mainly by the filament section53 whereupon the strip 49 is gradually heated to the extent ofdeflecting into'electrical contact with the lead 51. When such occurs,the portion 53 of the filament is shorted out causing a di'rninishingofthe light output of the lamp corresponding to that produced by thefilament section 53. As the strip and mass gradually cool allowing thestrip to separate from the lead 51, the filament section 53 is againenergized to result in a maximum brightness of the lamp. By such anarrangement, instead of the usual on and oil flashing, as may commonlybe expected from a lamp of this type, a pleasant twinkling afiect isproduced as the result of the continually changing light intensity ofthe lamp.

It is understood that with the device of Fig. 8, the filament sections52 and 53 may be of any length suitable for the purpose and positionedas necessary with respect to the mass 54 to produce the particulareflect desired. Further, the mass 54, as with masses 12 and 36, may beof any shape or size required to produce the delayed reaction intended.

While herein has been illustrated and described certain preferredembodiments of the present invention, it will be understood that variouschanges in the construction, operation, and characteristics of the partsmay be resorted to without departing from either the spirit orscope ofthe invention as now claimed.

I claim:

1. A flasher lamp including in combination a filament, leads to theterminal ends of said filament to eflect the energization and heatingthereof, a thermal strip disposed and heated by the filament to controlthe radiant heating and cooling of said strip.

2. In a flasher lamp the combination of a filament, lead means to theterminals of said filament for energizing and heating the latter, abimetallic strip movable when heated to interrupt current flow throughsaid filament to effect the cooling thereof, and a heat absorbing membersubstantially inclosing said bimetallic strip and heated by the filamentfor controlling the rate of heating and cooling of said bimetallicstrip.

3. In a flasher lamp a filament, leads for supplying energizing currentto the filament, a bimetallic strip mounted for electricallyinterrupting current flow through the leads for controlling the heatingand cooling of the filament,

and a heat absorbing member positioned for receiving heat from saidfilament substantially inclosing said himetallic strip for applyingradiant heat uniformly to the strip over substantially its entire lengthto eflect the controlled heating and cooling of the bimetallic strip.

Davis Mar. 18, 1941 Davis June 8, 1948

